'Europe/Madrid' timezone doesn't match 'Etc/GMT+1'

Question

I'm trying to convert a UTC timestamp to one in the Spanish timezone.

>>> import datetime as dt
>>> import pytz
>>> today = dt.datetime.utcfromtimestamp(1573516800)
datetime.datetime(2019, 11, 12, 0, 0)

>>> today.replace(tzinfo=pytz.timezone('Europe/Madrid')).timestamp()
1573517700.0

>>> today.replace(tzinfo=pytz.timezone('Etc/GMT+1')).timestamp()
1573520400.0

I'm surprised that I get different results for Europe/Madrid and Etc/GMT+1. Why is this? Should Europe/Madrid be used differently, or it is possibly a bug?

have you tried `.astimezone(pytz.timezone('Europe/Madrid')) `? — luigigi, Nov 12 '19 at 14:41
@luigigi Yes. The problem is that `today.astimezone(pytz.timezone('Europe/Madrid')).timestamp()` returns the same timestamp I started with — ignoring_gravity, Nov 12 '19 at 14:44

score 6 · Answer 1 · answered Nov 12 '19 at 20:17

A few things:

Europe/Madrid is UTC+1 during standard time, and UTC+2 during summer time (aka daylight saving time).
Etc/GMT+1 is UTC-1 for the entire year. Note the sign is opposite what you might expect. See the explanation in the tzdata sources, and on Wikipedia.
Since Madrid is on UTC+1 on the date you gave, you would get the same result for that date if you used Etc/GMT-1. However, I don't recommend that, as you would then later get the wrong result for a date during summer time.
The Etc/GMT±X zones are intended to be used primarily for non-localizable scenarios such as tracking time onboard ships at sea - not for populated locations on land.
As Mason's answer showed, you should be using the localize function rather than replace to assign a time zone. This is covered in the pytz documentation.

Thanks, really appreciate this! Lesson learned - read the docs :) — ignoring_gravity, Nov 13 '19 at 09:29

Mason · Accepted Answer · 2019-11-12T15:51:00.017

4

UTC Timestamp: The number of seconds since January 1st, 1970 at UTC.

Python datetime: A nice way of seeing this time that is user friendly

The UTC timestamp is not effected by timezones, but the datetime is.

This code takes the given timestamp and converts it to a UTC datetime and a Europe/Madrid timezone.

import datetime as dt
import pytz

# define the old and new timezones
old_timezone = pytz.timezone("UTC")
new_timezone = pytz.timezone("Europe/Madrid")

# get an 'offset-aware' datetime
today = dt.datetime.utcfromtimestamp(1573516800)
my_datetime = old_timezone.localize(today)

# returns datetime in the new timezone
my_datetime_in_new_timezone = my_datetime.astimezone(new_timezone)

print("Old:", str(my_datetime), "\nNew:", str(my_datetime_in_new_timezone), "\nDifference:",
      str(my_datetime - my_datetime_in_new_timezone))

Output:

Old: 2019-11-12 00:00:00+00:00 
New: 2019-11-12 01:00:00+01:00 
Difference: 0:00:00

Code adapted from: Python: How do you convert datetime/timestamp from one timezone to another timezone?

edited Nov 12 '19 at 15:51

answered Nov 12 '19 at 14:54

Mason

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I tried running your code and got `TypeError: bad operand type for unary +: 'str'` – ignoring_gravity Nov 12 '19 at 14:57
I just fixed that, sorry – Mason Nov 12 '19 at 14:58
Thanks. But still, how do I get the new timestamp? – ignoring_gravity Nov 12 '19 at 14:59
@ignoring_gravity, I added the conversion code at the end. – Mason Nov 12 '19 at 15:08
Thanks - problem is, that returns the same timestamp we started with – ignoring_gravity Nov 12 '19 at 15:32
A timestamp, by definition, is in UTC. This is described at https://www.unixtimestamp.com/ The python datetime is the only thing that changes with the timezone. I am editing my answer to make things more clear – Mason Nov 12 '19 at 15:37
Yes. So, currently, `today` corresponds to: 12th of November, 2019, midnight. I would like the UTC timestamp corresponding to 12th of November, 2019, midnight, in the Spanish timezone. In other words, when in Spain it's midnight on the 12th of November 2019, what's the UTC timestamp? – ignoring_gravity Nov 12 '19 at 15:44
1

Actually, got it - I can just do `new_timezone.localize(today).timestamp()`. Your code helped me get to this, so I'll accept it – ignoring_gravity Nov 12 '19 at 15:59

'Europe/Madrid' timezone doesn't match 'Etc/GMT+1'

2 Answers2